


Mind My Business

by FullOfBoredom



Category: Undertale (Video Game)
Genre: Blightmare, M/M, Mind Sex, Telepathy
Language: English
Status: Completed
Published: 2021-02-14
Updated: 2021-02-14
Packaged: 2021-03-14 17:29:17
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,829
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29422359
Author URL: https://archiveofourown.org/users/FullOfBoredom/pseuds/FullOfBoredom
Summary: “Nightmare…”Blue’s sins crawled down his back, his own hands down his front. Fantasizing about others felt taboo, considering how he could always see their lewd scenarios and they couldn’t see his the same way, but once in a while...well he was a normal monster and he had needs. The fact that it was Nightmare, strong, smart, private Nightmare, the one who cut off his own fantasies early all the time for Blue’s own comfort constantly, made him feel guilty and hot at the same time.Or: Telepath Blue Gets Some
Relationships: Sans/Sans (Undertale)
Comments: 13
Kudos: 118





	Mind My Business

_ Hey Nightmare!  _ Blue focused on the thought hard, trying to send it across the multiverse. He could read his friend’s thoughts from anywhere now, with Nightmare’s help in honing the ability, but he had yet to send something back.

The theory was sound. Blue could hear thoughts at any range, so he obviously could form a connection to a mind, and thus should be able to send something through said connection, but Blue had yet to get anything through. He’d tried happy thoughts, angry ones, sad ones, and the closest he could get to neutral thoughts. Nothing. He’d almost given up on it entirely if not for the steady unwavering belief Nightmare held in him to eventually succeed. He wanted to have SOME progress to bring to Nightmare tomorrow when they did their weekly book exchange.

He took a deep breath and sat back on his bed. What was Nightmare up to right now?

_ Blue must be practicing again. I’ll ignore it for now, thoughts of him may give false positives. _ Another shot of that damn kiss that they still hadn’t enacted in reality. They hadn’t even really addressed the strange (thought chemistry?) thing between them that was unfolding around this weird half mentorship.

Blue touched his fingers to his teeth. Would Nightmare kiss him so chastely, or would he be handsy? His tentacles suggested the latter.

His mind wandered to the feel of them, sliding over his arms, slick and heavy yet secure in their hold while Nightmare kissed him. One would wrap around his back, pressing them together while Blue responded enthusiastically to the kiss. He didn’t get to have much fun lately with everyone being in a committed relationship, Blue’s options had gotten limited.

He traced over the top of his sternum, catching the bones under his neckerchief but above his shirt line. He pressed down to scratch. Nightmare nipping would make him sting just enough to make his legs shake.

“Nightmare…”

Blue’s sins crawled down his back, his own hands down his front. Fantasizing about others felt taboo, considering how he could always see their lewd scenarios and they couldn’t see his the same way, but once in a while...well he was a normal monster and he had needs. The fact that it was Nightmare, strong, smart, private Nightmare, the one who cut off his own fantasies early all the time for Blue’s own comfort constantly, made him feel guilty and hot at the same time.

He couldn’t stem the tide once the dam broke, lost in the idea of it. Nightmare would easily overpower him in a one on one. Blue had such a hard time getting in the mood with partners, their strays thoughts his own and their criticisms more so, but Nightmare would know and avoid the traps. 

“Mweeeeeh.” He’d removed the gloves, phalanges already caught in the gaps between his ribs under his thin shirt. Blue hummed into the sparks, pleasure small and catching to kindle a greater pleasure as he roughly twisted round his sensitive bone divots, focusing on nothing else until the pulse of his own magic begged for form. It came to life instantly with only the desire to do so.

Would Nightmare prefer him to have an ecto body or bare bones? 

He’d want whatever Blue preferred. He didn’t strike Blue as picky about such small details, more so about his partner in general or perhaps his own fulfillment. He slid off his shirt with only a cursory check of the house to see if his brother was there.

“I’d better not drag this out too long.” He had practice to return to at some point. With the single mind of working himself up, he dug through his bedside table to prep his playthings. 

His hips rocked from his kneeling position, eyeing his little setup hungrily, cupping his chest while he let the fantasy wash over him.

Nightmare, having already made out with him, would move them to somewhere more comfortable ( _ like the bed he was already on _ ), each tendril given a special assignment to ignite the core of his body through the sensitive zones he’d have already dedicated to memory. They’d poke and prod, leaving Nightmare himself the honor of pinning him back against the mattress with his own arms.

He’d take his sweet time, enjoying the overwhelmed look on Blue’s face. His tentacles would hold his legs apart, grinding up against his pubis with a smirk, eye hazy with pride and amusement, leaving his pants on to further Blue’s frustration just a bit further. 

“ _ Little telepath, how did you find yourself captured like this? _ ” Blue rubbed his areolas in slow circles while imaginary Nightmare whispered into his ear. “ _ You had so much warning, did you want this? _ ”

“Yes.” He choked on the shameful whisper, fingers slipping down to take the gathering slick for a taste of the heady arousal. 

His head clouded, reaching for his vibrator while he ground up into his fantasy partner, suddenly hoping that Nightmare used his tentacles to hold him up high for the inevitable drop onto his cock. He dragged his hand through his soaked folds to pull himself higher. The wet taste of it pushed him closer and closer under the influence of lust and the steady hum of his toy against his still hooded clit to keep it bearable. He’d about hit a point where he’d settle for leaving the dildo at his side untouched, already built to a respectable orgasm, when a thought came in clear as a bell.

_ Did I say you could come? _ Blue pulled the vibrator back just in time, body so close to taking the plunge, nerves singing with disappointment at the edge.

“Nightmare?” Blue was in a haze, but he knew that voice, and he hadn’t thought up that response.

_ You finally send a thought and it’s about you desperately wanton over my attention.  _ Blue gasped at the reflection of his own fantasy shown back to him.  _ Now that you’ve involved me in this little escapade, I have a few ideas. _

Blue kept a steady pace with his index and pointer fingers while Nightmare treated him to the lovely image of himself, bound at the hands, naked body pressed back against Nightmare’s. 

_ Show me how wet you are. _

Blue pulled his fingers away from his quivering cunt, a line of unbroken slick dragged with them when he took a glance. Nightmare’s purr thrummed through his chest.

_ I could have so much fun with you.  _ Fantasy Nightmare hooked his chin over his shoulder to play with his entrance, now accurately soaked under his fingers to ease the push into him. Blue’s own hands mirrored it, panting out tiny huffs for Nightmare to hear through their shared dream.  _ You want my cock this bad? _

“Don’t make me say it.” Blue’s whines only fueled the smug smile he could feel over his shoulder.

_ If you don’t, I won’t give you what you need.  _ Blue huffed defiantly, but conceded the point.

“Stars, fuck me Nightmare!” His hand trailed to his dildo. Nightmare dressed his collar in featherlight kisses as a reward, waiting patiently for Blue to position the toy for the next step.

_ How could I deny such an earnest request? _ Nightmare changed their fantasy around enough to have Blue face him, held up by his appendages directly over his now actual imaginary cock. Blue’s mouth watered much to his amusement.  _ See something you like? _

“Mw-wehhh. You look t-thicker than I thought.” His toy wouldn’t do it justice besides the very real stimulation it’d provide over just the hyper horny thoughts flooding his brain.

_ I’ll let you test that theory when you visit next.  _ Blue whined as he was slowly lowered, tentacles content to let him slide down slowly, letting him push in the dildo at the same time. He could hear Nightmare groan when he heard Blue’s body clench around it through the feedback, his own thoughts growing more scattered with Blue’s own.  _ You’re ruining me _ .

“No, that’s you ruining ME.” Blue bucked into the long toy, licking his teeth in time with Nightmare’s slow thrusts his wrists tried to match.

_You could be messing with me on purpose, but I am much too affected to care._ A break from the scene, Nightmare appeared behind his eyelids, standing in his bathroom staring down his own reflection with a look that spoke of something uncontrolled in the way his thoughts weren’t. Only a flash, possibly not meant to be shared at all, but that desperate look pulled a whimper out of him that raised him back onto his knees to fully seat himself and look off the bed.

His desk mirror framed his smooth ectobody. His confident posture hadn’t faltered, proud and tempting with his tongue stuck out for his sole audience. He had one hand behind his head, gripping his neckerchief tight against his cervical vertebrae, the other dropped down to hold open his eager lips sucking in the dildo he rode hard, slow but powerful drops that left his legs trembling with each one. 

_ Fuck Blue, I’m getting so- _

“Did I say that you could come?” Nightmare’s groan hit his ears, Blue’s soul glowing like a solar flare, full of pride and entirely too alluring for the negative guardian. His hazy eyelights full of mirth and hunger got wilder with the surge of intent from Nightmare’s mind.

_ Such a satisfying meal.  _ Purposeful this time, Blue got a view of Night in front of the bathroom mirror, growling and wild, dick in his hand while pinned down Blue with his leering alone. He’d devolved from the proper stance, tentacles poised dangerously, his corruption shifting and loose. Blue could see his teeth had sharpened into pointed fangs.  _ Sin looks so good on you little telepath. _

Blue didn’t waver. Nightmare couldn’t scare him off that easily, especially so close to cumming while five inches deep on his imaginary cock.

“I bet it’d look even better in me.” He escalated the pace to unrelenting, screaming out for him. “Please, Nightmare!”

_ Come for me Blue! _

The wave crashed over Blue hard, body locking up under the pleasure, tightening around the dildo with a wail. The echo of Nightmare’s own gasp of his name sent him half catatonic.

The wave ceased after many long minutes, Blue having collapsed onto his bed in a daze. 

_ Blue? _ Nightmare called out for him. Blue found the thread with ease.

_ I’m alive. _ Now that it’d been in his hands, the ability jumped into his hands like an old friend. Another skill, another new piece of himself, all thanks to Nightmare.

_ That’s about where I am as well.  _ Nightmare’s tired chuckle had Blue laughing along. He didn’t know what was coming next now, considering the steps taken, but he DID know what he wanted.

_ Same time tomorrow? _ Nightmare’s small confused pause and then quiet realization left Blue hanging on his next word, but as always, he needn’t have worried.

_ I look forward to it. _


End file.
